Hot Bullet Casings Can Finger the Criminal,Says UK Scientist

Forensic scientists could soon be pulling fingerprints from fired bullet casings, a technique not unlike one used by Batman to track down the Joker in this year's summer blockbuster.

Despite advances in DNA technology, fingerprint identification remains an important forensic tool. In the UK, twice as many car thieves are caught by fingerprint identification as by DNA evidence.

Fingerprinting dust clings to organic compounds like amino acids and urea from skin to reveal prints. But any of those residues on a bullet are likely to be burned away when it is fired, typically reaching temperatures above 200°C.

Now John Bond, a scientist with the Northamptonshire Police and fellow at the University of Leicester, both in the UK, has discovered that fired bullet casings can reveal fingerprints. And it is the high temperatures they reach that make it possible.
Etched prints

When a gunman loads a cartridge into their gun tiny quantities of salty sweat from their fingers are transferred onto it, recording an impression of the fingerprint.

Firing the gun rapidly heats the casing, vaporising the water in the sweat. "You're left with non-volatile salts," Bond says. Established fingerprinting techniques ignore those residues, but they can reveal prints, he has discovered.

"At high temperature, those salts are molten and you get a chemical reaction with the metal." Those reactions chemically etch the fingerprint into the surface of the bullet casing when the cartridge is fired – and no amount of washing or wiping will remove it.

"Even if heat vaporises normal clues, police will be able to prove who handled a particular gun," says Bond.
Brass rubbing

However, the technique only works with certain metals, Bond explains. Reactive metals like zinc and aluminium oxidise naturally in the air, becoming coated in a layer of oxide that prevents the fingerprints from corroding the metal.

"At the other end of the spectrum, gold and platinum are so unreactive that fingerprints don't react with them at all." The best results are found with copper, a key component of brass. "Fortunately most shell cases are made from brass," says Bond.

Bond says gunmen without sweaty fingers can also be traced from heated bullet casings. "There might not be any salty sweat present, but the fatty sebaceous glands will deposit fats and waxes on the metal," he says.

Those fatty deposits also record an impression of the prints. When the metal is heated up, its surface becomes oxidised. "But the fatty deposits inhibit that oxidation, so you end up with nice shiny brass where the fingerprint was deposited, and dull brass surrounding it."

Bond's team has already processed bullets provided by the US and UK police, and the technique could also be crucial in identifying terrorist bombers. The researchers have already talked to the military about using the technique in Afghanistan. "Bombs are likely to be made from dense metals like copper," says Bond. "The science should work in the same way."

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Nolo

August 31, 2008, 06:13 PM

Okay, so now the UK is taking it's cues from Batman!?
I mean, I know it was a good movie, but geez...
I seriously don't know what to think of this.
Against average criminals, it would probably be a good thing.
Against crime bosses... either useless or worse.
At least it doesn't cost us like microstamping...

Duke Junior

August 31, 2008, 06:27 PM

Okay, so now the UK is taking it's cues from Batman!?
I mean, I know it was a good movie, but geez...

I enjoyed that part too,Nolo!That's why why I threw out this article.
Is this real or is this more BS?Should I add a ? mark on the headline?:D

Marcus84

August 31, 2008, 06:31 PM

Why would they test this? There are no guns in the UK.

Aaryq

August 31, 2008, 08:13 PM

1. All of you brassfetchers out there may be doomed.
2. In a recent press release, the GLC (Global League of Criminals) as announced that they have officially switched to Wolf, Silver Bear, and Brown Bear ammunition.

1911Tuner

August 31, 2008, 08:42 PM

And all this high-dollar, high-tech mumbo-jumbo can be nullified by simply using a revolver or any other non-autoloading weapon.

sacp81170a

August 31, 2008, 08:48 PM

And all this high-dollar, high-tech mumbo-jumbo can be nullified by simply using a revolver or any other non-autoloading weapon.

Or wearing disposable rubber gloves when handling weapon and ammo, or wiping prints off ammo before loading....

RP88

August 31, 2008, 08:50 PM

load it with gloves, glue a plastic bag over the port, revolver, steel-case, shotgun shell...

wow, thought of those without any effort at all

TallPine

August 31, 2008, 08:54 PM

Heck, just use a cap & ball pistol: no casings at all :D

Duke Junior

August 31, 2008, 09:02 PM

Heck, just use a cap & ball pistol: no casings at all ;load it with gloves, glue a plastic bag over the port, revolver, steel-case, shotgun shell...

wow, thought of those without any effort at all

And all this high-dollar, high-tech mumbo-jumbo can be nullified by simply using a revolver or any other non-autoloading weapon.

Or wearing disposable rubber gloves when handling weapon and ammo, or wiping prints off ammo before loading....

And none of you are "prestigious" UK scientists making your commonsense findings even more impressive!:D

Not unlike batman? Really? Once again journos proving how little they know about the subject they are writing on. In the batman movie they got the thumbprint from the bullet lodged in brick. I don't think the author knows that the casing stays behind...

Threeband

September 1, 2008, 08:47 AM

I've heard that it's common practice among some criminal types to wipe the prints off their cartridges as they load up.

Still, it's amazing how careless, sloppy, stupid so many criminals are. It's been known for over a century that wearing gloves prevents leaving fingerprints, yet most crimes are committed with ungloved hands.

For a lot of members of that vast under-stratum of society, crime is less an isolated event, and more a part of daily life. They seem to just drift along thoughtlessly, drinking, fighting, stealing, and bad things just somehow happen to them. They seem to lack an awareness that every action they take reflects a choice, and has consequences.

The jails are full of people who can't quite seem to figure out why they're there.

Anyway, these types won't wear gloves, or wipe their prints, or police their brass.

highlander 5

September 1, 2008, 08:56 AM

Gold and platinum shell casings???? If I had that kind of money I wouldn't have to steal for a living

ZeSpectre

September 1, 2008, 09:25 AM

Removed non-high road comment.

Vern Humphrey

September 1, 2008, 09:50 AM

What's the difference between a "bullet casing" and a cartridge case?:p

Lashlarue

September 1, 2008, 10:38 AM

Latex gloves cost pennies and if you are not on file, like most nowadays.This high tech CSI BS is just that....

AndyC

September 1, 2008, 11:18 AM

I read it as meaning that it's the reporter comparing the technique to Batman, not the scientist getting his idea from Batman.

AndyC

September 1, 2008, 11:20 AM

It's the reporter comparing it to Batman, not the scientist getting his idea from Batman.

Then again, life imitates art more than we might imagine.

sm

September 1, 2008, 11:20 AM

Vern Humphrey wrote:
What's the difference between a "bullet casing" and a cartridge case?

Bullet casing allows one to go first going through the food court downstairs in the Scientific Building, and one's cronies lets you have the good seat at the table so you can see out the window in the dining area.

*i-say-dear-chap*

Crunker1337

September 1, 2008, 12:00 PM

There are numerous ways around this that any fool can think of in a second.
Has ballistics tracing EVER been used to put a criminal behind bars?

sacp81170a

September 1, 2008, 12:04 PM

Has ballistics tracing EVER been used to put a criminal behind bars?

Only amateurs, more than likely. In order to place someone at a crime scene you have to have several elements, and it's not as easy as one would expect. Ballistic evidence alone would be pretty shaky without a whole bunch of other stuff to support it, CSI notwithstanding.

dalepres

September 1, 2008, 08:01 PM

Well, this is a non-issue for the District of Columbia where only revolvers will be permitted.

sacp81170a

September 1, 2008, 08:22 PM

Well, this is a non-issue for the District of Columbia where only revolvers will be permitted.

LOL! Who'da thunk it? DC's laws are written so as to help protect criminals from their own stupidity. :evil:

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